Suing for $20 million.A Central Park West mother of two has filed a $20 million lawsuit against the woman she claims ruined her life: her former nanny.

Michelle Padilla, author of “The Official Guide to Finding a Great Nanny and Keeping Her,” fabricated child-abuse claims against Danica Cordell-Reeh, 45, because Cordell-Reeh fired her – costing the mom custody of her 5-year-old twins, court papers charge.

“One day, my children had a full-time mother, and the next day, I was virtually out of their lives,” said Cordell-Reeh.

Cordell-Reeh’s lawyer, Bernard Clair, said, “This case represents the true underbelly of the ‘Nanny Diaries.’ [Padilla] worked for my client for 2½ weeks and did a lifetime of damage.”

The Manhattan state Supreme Court suit claims the accusation isn’t the first time Padilla has made up charges, and that the self-proclaimed “Park Avenue nanny” is also a former anorexic prostitute with a history of mental illness.

The mom hired Padilla through Nannies of St. James, a highly respected London-based agency, Oct. 8. On Oct. 24, Cordell-Reeh called the agency and said she’d like to replace Padilla because she was refusing to do housework.

That same day, Padilla packed up her belongings and left without giving any notice, the suit says.

The next day, Padilla went to the mom’s estranged husband, investment banker Henry Owsley III, and told him the mother had been sexually abusing one of the children and wasn’t feeding them, the suit says.

She also called child welfare, the family’s therapist and the kids’ school, telling them the same tale, the suit says.

The worried dad rushed into court with an affidavit from Padilla on Oct. 26, and got custody of the kids.

A suspicious Clair hired a private investigator to check out Padilla’s references.

One of them, identified as Christopher R., was “shocked” to discover he’d been listed as a reference and had written a recommendation, Clair said. “His reaction was, ‘I have to sit down,’ ” the lawyer said.